CN706 is an attenuated, replication competent adenovirus that has been genetically modified to replicate preferentially in human PSA-producing prostate cells. Preclinical studies of CN706 have demonstrated that it can effectively generate an oncoltic infection in PSA-producing cells and xenograft tumors. Patients who have failed primary radiation therapy for prostate cancer, as evidenced by a steadily rising PSA, have a poor prognosis; the majority will go on to develop matastatis disease.